Dirt Rag Magazine

Review: GT Sensor

By Shannon Mominee

Last August 2010, GT unveiled their revamped 2011 product line in Les Deux Alpes, France and re-launched the GT brand. Their hope is that a generation of riders not familiar with their previous dominance on the race scene would come to perceive GT as a company providing affordable tried and true, durable products. Unveiled were more bikes with 29” wheels, bold frame colors, color-matched components and parts spec’d to give riders what they need without upgrading. I was lucky enough to attend and rode the Sensor 29R Pro with 120mm of full-suspension and the 26”-wheeled Sensor 1.0. When the Sensor 29R Pro arrived for test, I was excited to have another chance to ride it on the roots and rocks.

The Bike

The Sensor is part of GT’s Endurance line of mountain bikes aimed at riders looking for an all-around, durable bike. For 2011 the Sensor is offered with 29” or 26” wheels. Both share the same swoopy top tube and suspension design, with tweaks in the geometry for the respective wheel size. The Sensor 29R Pro is their top-of-the-line offering and has a hydorfomed, 6061- aluminum frame with 120mm of rear travel. It uses GT’s proprietary i-Drive suspension system. For those unfamiliar with i-Drive, the design utilizes an isolated bottom bracket that receives input from the dogbone-shaped i-Link to minimize chain growth and reduce pedal feedback. A small amount of chain growth is preserved, however, to provide pedal-induced anti-squat resulting in more effective power transfer to the rear wheel (see issues #149, #135 and #110 for more on i-Drive).

Like all i-Drives, the Sensor has two pivot points that are positioned one above the other, both slightly forward of the bottom bracket. The pivots use readily available 1 1/8” angular contact headset bearings that are simple to adjust for proper bearing preload. The Sensor 29R Pro is spec’d with a Fox Float RL rear shock and F29 RLC FIT 120mm fork with a QR15 thru-axle. GT All Terra hubs laced to DT Swiss M520 rims with Kenda Small Block Eight 29×2.1” tires handle the rolling duties. The bigger wheels bump up the rotor size over last year’s 26” model and Avid Elixir 5 brakes with 185mm rotors, front and rear, provide stopping power. SRAM’s 2×10 drivetrain completes the package with X7 shifters and front derailleur with an X9 rear derailleur. The double chainring is geared 39/26t with an 11-36t cassette. If you prefer a triple chainring, the 29R Expert is geared as such, but I found the 10-speed completely adequate for everything from steep, 21% grade fire roads in France to sustained singletrack climbing in North Carolina.

On the Trail

Riding portions of the Pisgah trail system near Asheville, NC, I was happy to be on a dually that pedaled uphill in a solid fashion. My size large tester had a 604mm top tube and a 90mm Syncros stem that fit my stature comfortably. The Sensor’s pedaling performance was solid enough that I didn’t use the platform damping and left the ProPedal in the “off” position. I could stay seated, keep the motor spinning, and let the rear tire roll over the obstacles and through rock gardens without breaking traction as I made my way up climbs. The longish, 454mm chainstays helped keep the front end planted. The bike’s center of gravity rides high due to a relatively high bottom bracket. The height did provide enough clearance spin over obstacles without catching a pedal but is was noticeable when cornering slowly. On long sections where standing was required, I flipped the lever to activate the ProPedal, locked out the Fox fork, and continued on.

I appreciated the leverage the 700mm wide Crankbrothers bar provided and although the suspension moved slightly from my standing, it was an acceptable amount and I didn’t feel much energy was wasted. The frame and linkage didn’t exhibit any twisting or stickiness and didn’t make any creaky noises, even after multiple stream crossings. On downhill sections the Sensor tracked well and handled drops with ease, while the fork and i-Drive soaked up blows from rocks that came too fast to swerve around. When catching air it was good a feeling to land into the plush suspension without bottoming it out.

The 1155mm wheelbase provided a good balance of stability and control at speed but felt a little sluggish going slow around tight turns. I’ve ridden pretty diverse trails aboard the Sensor 29R from rolling down the Alps on hard packed, wide-open curvy trails with tall berms that were perfect for carving high and diving out of, to the tight and twisty narrow single track of the east coast. Compared to other bikes I’ve tested with steep 70°-72° headtubes, the slacker 69.5° angle of the GT lent more control at speed downhill. The bike liked to be leaned heavily into corners to carry the momentum through the exit. As I mentioned, the center of gravity is high on the bike and the wheelbase long, so when cornering slow, turns need to be taken a little wider.

Final Thoughts

A 120mm full-suspension rig with 29” wheels should be able to crush rock gardens, plow through mud, make small work of logs or downed trees, and not be a burden when the trail turns skyward. It should also be able to handle tight and twisty singletrack and tackle descents. The Sensor 29R is a balanced bike—it’s a capable climber and a ripper on everything else. Steering is a little slow on really tight turns but comes alive at speed. This bike lived up to my expectations, and to the company’s reputation, of being a durable and capable bike with a proven suspension design.

At nearly 30lbs. this isn’t the lightest bike, but it doesn’t claim to be. It is, however, a bike that would fit a rider pedaling long hours while venturing on epic rides over rough terrain, or someone that partakes in 24-hour racing. It’s a great all-around trail machine that can tame the toughest trails. I like that it didn’t leave me feeling beat up or fatigued after 3-hour rides. Three grand for an aluminum 120mm, 29” dually with a 10-speed drivetrain and quality components is a respectable price, and a value considering the Sensor’s durability and adaptability to varying terrain.

Tester specs

  • Age: 38
  • Height: 6′
  • Weight: 183lbs.
  • Inseam: 33”

Bike specs

  • Country of origin: Taiwan
  • Price: $3,000
  • Weight: 29.9bs.
  • Sizes available: M, L (tested), XL
  • Online: www.gtbicycles.com

Keep reading

This review originally appeared in Issue #156. You can order a copy of this issue and other back issues in our online store, or order a subscription today and you’ll get all our reviews as soon as they are published.

 

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